Indoor networks are increasingly being used in businesses and homes to provide network connectivity over a small area such as an office building or home. Indoor location devices are often based on Wi-Fi and many function as a wireless local area network (WLAN). The network consists of multiple nodes that provide Wi-Fi signals to devices within range. A typical WLAN has at least one Access Point (AP) node and a plurality of Station nodes (STA) which can each communicate with the Access Point with which it is associated. It is becoming increasingly important for each node to determine and maintain information about its precise location as well as its position relative to the other nodes in the network. Such capabilities are generally termed “location awareness” and are considered desirable currently as well as being anticipated to be widely available in the future.
A current standard for carrying out location awareness requires that explicit data packets be sent between nodes to measure round-trip time (RTT) which requires a substantial amount of overhead and reduces network throughput. Under conventional techniques, RTT is measured from an explicit packet exchange comprising 1) a Timing Measurement Request Frame, 2) an acknowledgement (ACK) frame, 3) a Timing Measurement frame and 4) an ACK frame. Moreover, because RTT is the current positioning parameter, only the relative distance between an AP and a STA can be determined. To compute the two-dimensional location of a STA, at least three APs are required. Such a requirement results in a substantial number of packet exchanges and reduces network throughput. Basically, in the current implementation for estimating a position of a wireless node (STA), round-trip time to an AP is the usual available information which provides only relative distance based upon the speed of light. Each STA must then determine RTT to two additional APs to, in effect, triangulate its location using at least three independent RTT measurements.
There is therefore an existing need to carry out node location assessments while reducing the number of packet exchanges required and thus reducing network overhead. It would also be desirable to provide location awareness by using only one AP for a plurality of associated STA nodes to determine their respective locations in a network. The techniques of this disclosure satisfy these and other needs as will be appreciated in view of the following materials.